With temperatures heading to the 70s on Saturday and robust bursts of tree pollen a near certainty, all signs indicate that the baseball season has supplanted the 2018-2019 snow season, one that didn’t measure up to its preseason billings.
The 17.1 inches recorded at Philadelphia International Airport during the season was about 75 percent of normal, and the biggest chunk of it came in mid-November. Yet again, the winter temperatures were on the mild side.
While it wasn’t an especially punitive season — 90 percent of the precipitation was rain — it was another rough one for some of the seasonal outlooks that were calling for well-above average snow around here and all along the Amtrak corridor, and an especially wintry February.
Snow was plentiful farther inland — it was near normal in Allentown, and over 100 inches fell upon Burlington, Vt. — but New York City’s snow was about 80 percent of normal; Boston’s, 65 percent.
So, what went awry?
Conspiring against the forecasts were what did or didn’t happen in the tropical Pacific, the North Atlantic, and the west coast of Alaska, according to meteorologists.
But while they say they are making progress in this often Quixotic exercise, they continue to wrestle with an overarching mortal enemy — what Mike Halpert, the veteran seasonal forecaster at the government’s Climate Prediction Center, calls “random natural variability,” further compounded by background warming. In the short term, the outlook for the outlooks is cloudy, with a high probability of humility.
“We are dealing with a chaotic fluid medium in which there will always be one factor or another that can create unexpected results,” said Steven DiMartino, meteorologist with weatherconcierge.com.
The major outlooks actually got off to a decent start by calling for a generally gentle start in December in the East. AccuWeather predicted a December average temperature of 1.5 degrees above normal in Philadelphia; it was 1.4. That hot streak lapped into January, which it said would be “normal”; it finished a mere 0.3 degrees above.
But as Halpert said, “Then, February hit.” That’s where just about all the outlooks went to die, said Paul Pastelok, AccuWeather’s chief seasonal forecaster.
″Even in mid-January, it was looking good," Schwartz said.
“The pattern was setting up to be highly favorable for cold and snow,” he said. “Then the pattern suddenly collapsed.”
All the preseason outlooks counted on development of El Niño, the anomalous warming over a continent-size patch of the tropical Pacific. Typically it generates west to east winds that juice up a southern storm track, which can lead to strong storms that make a left turn up the Atlantic Coast. The warming eventually took hold, but too late to have a dominant impact on the U.S. winter.
“The forecast for El Niño to become established was a total bust, which had a direct impact on the storm tracks,” said DiMartino.
Also, a pressure pattern known as the North Atlantic Oscillation consistently worked against coastal snowstorms, Schwartz said. When air pressures are higher over the Arctic than they are at mid-latitudes, the NAO’s negative phase, they favor cold and snow. But the NAO remained positive throughout the winter.
Pastelok said unusual warmth off the west coast of Alaska might have been a factor in displacing cold and storm tracks. Snowpacks in parts of Iowa, Minnesota, and Wisconsin have contributed to the extreme Midwest flooding.
For now, forecasters advise, it is unreasonable to assume that a three-month outlook is going to hit all or even most of the targets. Nothing happens in a vacuum in the atmosphere, and weather systems interact with everything in their environments. As scientist Edward Lorenz famously remarked: “The flap of a butterfly’s wings can be instrumental in generating a tornado.”
“Winter forecasts are part science, part speculation, and part entertainment,” said Schwartz. “We do them each fall largely because the viewers demand it.”
The government sticks to probabilities of above- and below-normal precipitation and temperature, and stays away from specifics such as snow totals, a recognition of the limits of the science, says Halpert.
Pastelok said that those in the long-range business are riding a steep learning curve about how weather in one part of the world affects another part.
“There is so much we still don’t understand,” said DiMartino. “Since we are in baseball season, the best way to become a major league baseball player is to face major league pitching and fail.